1. Field
This disclosure relates to fuel systems and methods for engines and more particularly to a system and method for producing low-sulfur fuel from bulk fuel onboard a vehicle while the vehicle is in transit.
2. General Background
Sulfur content in hydrocarbon fuels used in various modes of transportation ends up in the atmosphere in the form of pollutants including oxides of nitrogen (NOX), oxides of sulfur (SOX), acid rain and particulate matter (PM), resulting in significant adverse effects on public health. Certain national and regional governments, especially in the developed world, have undertaken programs to require reduced sulfur content in transportation fuel supplies to mitigate this problem. Such measures can make a substantial impact on emissions from ground transportation vehicles where fuel providers in this market clearly fall under the jurisdiction of such national and regional governments.
In contrast, operators of ocean-going vessels and international commercial aircraft by necessity obtain fuel throughout the world, often in areas where fuel specifications, especially sulfur content, are not so tightly regulated. Ocean-going vessels and aircraft will carry into and continue to use this “dirty” fuel in areas more sensitive to pollutant air emissions. For example, cargo and tanker ships calling at the Port of Los Angeles will continue to burn the “dirty” fuel with which they were filled elsewhere while they are near or in the Port, contributing to the region's air quality problems.
Incentives to “clean up” fuel supplies on a global scale will not be in place in the foreseeable future. Combustion engine exhaust gas after-treatment systems are actually poisoned by sulfur such that their use for sulfur cleanup is not possible. Achieving low sulfur emissions therefore has depended on the availability of low sulfur fuel. This represents the prior art for achieving low sulfur emissions from ocean-going vessels and commercial aircraft. What is needed, then, is a mechanism to reduce the sulfur content of fuels before entry into combustion engines onboard the vehicles using these “dirty” fuels.